Control of a luminous flux of an operating lamp with respect to color temperature, intensity and distribution over a light emitting surface can be realized with operating lamps having conventional illumination means, such as halogen or gas discharge lamps. A color temperature of halogen or gas discharge illumination means can be adjusted, for example, using filter techniques. The color temperature can also be changed when several illumination means are used. Brightness can be adjusted using apertures, e.g., without changing the color temperature. With electric dimming, a change in brightness can also change the color temperature. In addition, distribution of the luminous flux over a light emitting surface can be changed through aperture techniques and/or with the use of several illumination means.
It is desired to improve activating of illumination means of an operating lamp with respect to adjustment of a color temperature and an intensity (brightness) of the operating lamp.